Hi mappers this is Kasami!
Here is my explanation for the use of func_train_rotating and path_corner!
So you create a plat that turns in the direction it moves.
The direction the plat moves depends on where you place 
the path_corners and how you set them. But there are still strange things
i couldnt figure out how to fix them. Like....i had to install the ladder
a way off the plat in the *.map file so that it appears at the right place
(at the plat in wait position) in the *.bsp file. If you take a ride with
the plat you will get squished when the plat turns. But it is`nt the goal
to get rid of those things in this example map. I just want to show you guys
how it general works.
In this example moves the plat pretty rough, Thats because i used just two
path_corners for a 90 degree turn. In this case you have to set each 
path_corner to 45,45!(rough move)
If you instead want to use 9 you have to set them like 
10,10,10,10,10,10,10,10,10(pretty smooth move)!
I put three files in the *.zip file like in any other 
*.zip file of mine. The *.bsp,*.map and the readme file. 
To see how it works check the *.bsp file out!
If you need any exact information just check the *.map file out 
and see how i did the settings!
If you got any questions or better ideas 
just feel free to contact me by E-Mail. "wolle@netmdc.com"
Cya and good luck!!!